Direct clinical relevance of IFITM3's involvement in restricting human IAV infection has recently been shown in individuals hospitalized with seasonal or pandemic influenza H1N1/09 viruses (15), where a statistically significant number of hospitalized patients show overrepresentation of a minor C allele in IFITM3 (rs12252-C) that correlates with a decrease in the ability of IFITM3 to restrict influenza virus infection in vitro. Here, IFITM3 is linked to influenza.